The combination of technological advances in Dental materials and increased demands in quantity and quality by a burgeoning population of dentate elderly has resulted in the production of new Dental restoration systems at an unprecedented pace. Longevity studies can no longer keep up with market-driven demands. This has placed increased importance on testing techniques and failure analyses. The goal of this project is to meet the needs of Dental professionals by understanding Dental restoration failure modes, produce guidelines and recommendations for improving Dental restoration longevity and disseminate the relevant information. The goals will be achieved in a series of steps. First, relevant application-based property testing techniques will be established, rather than material-based. This will help solve some of the current problems in the Dental field, where many different materials are now so advanced they can be used for the same application, but are still tested differently. Second, restoration-shaped specimens of the tested materials will be made and broken to mimic the fracture surfaces of failed restorations in vivo. The ability to reproduce a fracture surface represents a thorough understanding of the stress configuration and fracture progression. Only very recently have fractographic studies and a small collection of failed restorations enabled such an endeavor. Next, this project will continue to build a library of failed restorations, utilizing the newly established PBRNs. By collecting a statistically significant number of fractures, correlations with published longevity studies would finally be possible. The last goal is effective technology transfer, as this research has immediate practical value and scientific merit. Besides presentations and publications, an educational package will be made available for Dental schools, and information will be made available to practicing professions through the PBRN program and the resources of the ADA. This project will benefit the public by improving the quality and durability of Dental restorations. In order to avoid restoration failure, the role of properties, testing and fracture progression must be understood. This is of obvious value to researchers, but this knowledge and data will also be accessible for practicing Dentists, manufacturers and laboratory technicians to be able to work together to make informed choices regarding restorations within their own areas of expertise. [unreadable] [unreadable] [unreadable]